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Performance in self-paced endurance exercises results from continuous fatigue symptom management. While it is suggested that perceived responses and neuromuscular fatigue development may determine variations in exercise intensity, it is uncertain how these fatigue components interact throughout the task. To address the fatigue development in self-paced endurance exercises, the following topics were addressed in the present review: (1) fatigue development during constant-load vs. self-paced endurance exercises; (2) central and peripheral fatigue and perceived exertion interconnections throughout the self-paced endurance exercises; and (3) future directions and recommendations. Based on the available literature, it is suggested (1) the work rate variations during a self-paced endurance exercise result in transitions between exercise intensity domains, directly impacting the end-exercise central and peripheral fatigue level when compared to constant-load exercise mode; (2) central and peripheral fatigue, as well as perceived exertion response contribute to exercise intensity regulation at the different stages of the trial. It seems that while neuromuscular fatigue development might be relevant at beginning of the trial, the perceived exertion might interfere in the remaining parts to achieve maximal values only at the finish line; (3) future studies should focus on the mechanisms underpinning fatigue components interactions throughout the task and its influence on exercise intensity variations.

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Purpose: We sought to verify if alterations in prefrontal cortex (PFC) activation and psychological responses would play along with impairments in pacing and performance of mentally fatigued cyclists. Materials and Methods: Eight recreational cyclists performed two preliminary sessions to familiarize them with the rapid visual information processing (RVP) test, psychological scales and 20 km cycling time trial (TT20km) (session 1), as well as to perform a VO2MAX test (session 2). Thereafter, they performed a TT20km either after a RVP test (30 min) or a time-matched rest control session (session 3 and 4 in counterbalanced order). Performance and psychological responses were obtained throughout the TT20km while PFC electroencephalography (EEG) was obtained at 10 and 20 km of the TT20km and throughout the RVP test. Increases in EEG theta band power indicated a mental fatigue condition. Repeated-measures mixed models design and post-hoc effect size (ES) were used in comparisons. Results: Cyclists completed the trial ~2.7% slower in mental fatigue (34.3 ± 1.3 min) than in control (33.4 ± 1.1 min, p = 0.02, very large ES), with a lower WMEAN (224.5 ± 17.9 W vs. 240.2 ± 20.9 W, respectively; p = 0.03; extremely large ES). There was a higher EEG theta band power during RVP test (p = 0.03; extremely large ES), which remained during the TT20km (p = 0.01; extremely large ES). RPE increased steeper in mental fatigue than in control, together with isolated reductions in motivation at 2th km (p = 0.04; extremely large ES), felt arousal at the 2nd and 4th km (p = 0.01; extremely large ES), and associative thoughts to exercise at the 6th and 16th km (p = 0.02; extremely large ES) of the TT20km.Conclusions: Mentally fatigued recreational cyclists showed impaired performance, altered PFC activation and faster increase in RPE during a TT20km.

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This study aimed to assess the relationship between an uphill time-trial (TT) performance and both aerobic and anaerobic parameters obtained from laboratory tests. Fifteen cyclists performed a Wingate anaerobic test, a graded exercise test (GXT) and a field-based 20-min TT with 2.7% mean gradient. After a 5-week non-supervised training period, 10 of them performed a second TT for analysis of pacing reproducibility. Stepwise multiple regressions demonstrated that 91% of TT mean power output variation (W kg-1) could be explained by peak oxygen uptake (ml kg-1.min-1) and the respiratory compensation point (W kg-1), with standardised beta coefficients of 0.64 and 0.39, respectively. The agreement between mean power output and power at respiratory compensation point showed a bias ± random error of 16.2 ± 51.8 W or 5.7 ± 19.7%. One-way repeated-measures analysis of variance revealed a significant effect of the time interval (123.1 ± 8.7; 97.8 ± 1.2 and 94.0 ± 7.2% of mean power output, for epochs 0-2, 2-18 and 18-20 min, respectively; P < 0.001), characterising a positive pacing profile. This study indicates that an uphill, 20-min TT-type performance is correlated to aerobic physiological GXT variables and that cyclists adopt reproducible pacing strategies when they are tested 5 weeks apart (coefficients of variation of 6.3; 1 and 4%, for 0-2, 2-18 and 18-20 min, respectively).

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UNLABELLED: The monitoring of distance is crucial to calculate the metabolic requirement and the ratings of perceived exertion (RPE) for a given exercise bout. Visual cues provide valuable information for distance estimation, navigation and orientation. The present study investigated if light deprivation may affect the conscious monitoring of distance, RPE and associative thoughts to exercise (ATE) during a 20-km cycling time trial (TT20km). Eleven male, endurance cyclists performed two TT20km in illuminated-control and light-deprived laboratory. They were asked to self-report RPE and ATE when they perceived they had completed each 2km. RESULTS: The light deprivation resulted in elongated perceived distance at each actual 2km, rather than in illuminated-control trial (P<0.05). Although there was no difference in RPE when it was plotted as a function of the perceived distance, RPE was lowered in light-deprived environment when it was plotted as a function of the actual distance (P<0.05). Additionally, ATE was lowered during TT20km in light deprivation (P<0.01); however, pacing and performance were unaffected in light-deprived environment. CONCLUSION: Results suggest that pacing and performance were regulated through a system which was unaffected in light-deprived environment, despite the altered conscious distance monitoring and perceptive responses.

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This study examined the relationship between mood and rating of perceived exertion (RPE) during a simulated multiple-lap time trial (MLTT). Nineteen male cyclists performed a MLTT consisting of four 9.9 km laps, each lap with a gradient ranging from 0 to 10 %. Mood as measured by the Profile of Mood States Questionnaire (POMS) and perceived exertion as measured by the Borg CR100 scale (RPE) were obtained at the end of each lap. A categorical multiple regressive model, having median of POMS subscales as independent variables, was obtained to explain the variance in median RPE responses. Increases in POMS fatigue scores and decreases in POMS vigour scores were observed throughout the MLTT (P < 0.001). A linear increase in RPE during the MLTT was also observed (P < 0.001). POMS fatigue subscale scores accounted for 88 % of the variance in RPE during the MLTT (R(2) = 0.88, P = 0.002), and no other POMS subscale improved the final predictive model. With the exception of fatigue these results suggest that most aspects of mood do not have a discernable effect on RPE during a MLTT. The rate of increase in RPE can predict the MLTT endpoint.

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The objective of this study was to analyze the influence of the presence and absence of competitors on pacing, overall running performance, and mood state during a self-paced 3-km run. Nine recreational runners participated in this study. They performed the following tests: a) an incremental test to exhaustion to measure the respiratory compensation point (RCP), maximal oxygen uptake, and peak treadmill speed; b) a submaximal speed constant test to measure running economy; and c) two 3-km running time trials performed collectively (COL, head-to-head competition) or individually (IND, performed alone) to establish pacing and running performance. The COL condition was formed of a group of four runners or five runners. Runners were grouped by matched performance times and to retain head-to-head characteristics.A mood state profile questionnaire was completed before and after the 3-km running time trial. The overall performance was better in the COL than in the IND (11.75 ± 0.05 min vs. 12.25 ± 0.06 min, respectively; p = 0.04). The running speeds during the first 500 m were significantly greater in COL (16.8 ± 2.16 km·h−1) than in IND (15.3 ± 2.45 km·h−1) (p = 0.03).The gain in running speed from IND to COL during the first 400 m (i.e. running speed in COL less running speed in IND) was significantly correlated with the RCP (r = 0.88; p = 0.05). The vigor score significantly decreased from pre- to post-running in COL (p=0.05), but not in IND (p=0.20). Additionally, the post running vigor was significantly higher in IND compared to COL (p = 0.03).These findings suggested that the presence of competitors induces a fast start, which results in an improved overall performance and reduced post-exercise vigor scores, compared to an individual run.

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O teste contrarrelógio (TCR), ou teste de resistência com término previamente estabelecido pelas dimensões tempo ou distância, é utilizado como meio de avaliação do desempenho de corredores em uma situação com variação livre da velocidade.Tanto o aprendizado motor, isto é, a transição de uma situação nova para rotina,quanto o processamento de informações dimensionais, são aspectos cognitivos que podem influenciar o resultado do TCR. Portanto, procurou-se avaliar a influência da informação dimensional exclusiva do tempo transcorrido ou da distância percorrida na reprodutibilidade do desempenho (i.e. tempo total) entre dois TCRs em situação novidade. Adicionalmente, a estratégia decorrida de um TCR-rotina foi comparada ao TCR-novidade para avaliar a influência do aprendizado no desempenho. Para este fim, seis corredores amadores realizaram dois TCRs de 3000m (T3000)com 15 dias de intervalo como linha de base. O T3000 fazia parte da rotina dos últimos três anos de treinamento. Ao longo dos 15 dias, foram realizados duas duplicatas de TCRs-novidade com intervalos de 48h entre as repetições. Os TCRs-novidade duplicados foram testes repetidos em distâncias idênticas não vivenciadas previamente. Na duplicata 1, os corredores tiveram informação do tempo transcorrido e, na duplicata 2, da distância percorrida.Todos os corredores utilizaram aparelho GPS. Observou-se que a informação exclusiva da distância ou do tempo não influenciou a reprodutibilidade do desempenho do TCR-novidade.Contudo, os corredores apresentaram uma estratégia de corrida em “W”, com maior velocidade média,reproduzida apenas nos testes T3000-rotina. Portanto, os corredores apresentaram uma estratégia decorrida mais eficiente e específica no T3000-rotina que não foi reproduzida em distâncias similares em situação novidade. Aponta para o desenvolvimento de métodos de treinamento de corrida que aprimorem a transição da habilidade apresentada na rotina de treinamento para uma situação de novidade...

The time trial (TT) test, previously set by time or distance, is used to evaluate theperformance in a situation where power or speed is freely changed by the athlete. The motor learning,namely the transition between novelty to routine, and the processing of dimensional information mayinfluence the pacing strategy and time trial performance. Therefore, our purpose was to evaluate theinfluence of elapsed time or distance covered feedback on the reproducibility of performance (i.e. totaltime) comparing two TTs in novelty, that is, with dimensions never experienced before. In addition, thepacing of a TT in routine, that is, with dimension experienced several times, was compared with the TT innovelty to assess the influence of learning on performance. Six amateur runners performed two 3000m TT(3000TT) within fifteen days as baseline. The 3000TT was the test of routine for the last three years ofrunning training. Along the 15 days, two TT in novelty with different dimensions were duplicated with48h between each trial. Along the TT in novelty, runners had the feedback of elapsed time (duplicate 1) ordistance covered (duplicate 2), exclusively. All runners used a GPS device during the trials. We found thatexclusive information of elapsed time or distance covered did not influence the time trial’s reproducibility.Nevertheless, the runners showed a “W-shape” pacing, with the highest average speed only reproducedwithin the two 3000TT routine tests. Therefore, the runners showed a more efficient and specific pacingstrategy during the TT in routine which was not reproduced during the TTs in novelty with similardimensions. Our study highlights the importance of training methods that transpose the performance of aroutine ability to novel contexts...

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